Optocoupler with LIVE wire

The input will vary from 150VAC to 280VAC.If the supply is available means the LED have to glow....
I'm new to this circuit.So I don't known in-depth.I tried with hardware,if the voltage is low means the LED not glowing,so I changed the resistance value to low(56K). If the resistor value is low means when high voltage across the IC become faulty.
If the resistance value is high means,at low voltage the LED not glowing...
How to solve this issue and to make the LED glow in specified voltage range.

Re: Optocoupler with LIVE wire

Hi,

electronics works with voltage and current. you canīt calculate with "glow" or "faulty".
This is why there are datasheets. full of usueful values.

You need to specify at which input voltage RMS you want the LED safely to be OFF.
You need to specify at which input voltage RMS you want the LED safely to be ON.
(inbetween there is a grey area, LED might be OFF, dimmed, or ON)

Re: Optocoupler with LIVE wire

Originally Posted by KlausST

Hi,

electronics works with voltage and current. you canīt calculate with "glow" or "faulty".
This is why there are datasheets. full of usueful values.

You need to specify at which input voltage RMS you want the LED safely to be OFF.
You need to specify at which input voltage RMS you want the LED safely to be ON.
(inbetween there is a grey area, LED might be OFF, dimmed, or ON)

I removed the LED and it connected to controller for sensing purpose.And changed the resistor value to 5.5K 2WATTS.Now also their is no response from the optocoupler.The resistor is used as an pullup resistor for the controller.

Re: Optocoupler with LIVE wire

Hi,

sadly still no useful specifications.

Your calculation of the resistor is wrong.
You calculated 5.5kOhms.

this gives 280V/5500Ohms = 50.1mA

According datasheet 50mA is the absolute maximum limit. Once you cross this limit, just for a short moment - you risk to kill the device.
50mA is NOT the usual operating current.
Now you should know that 280V is the RMS voltage and thus the maximum voltage is 280V x 1.414 = 396V
at 5.5kOhms this gives a maximum current of about 72mA --> expect the PC814 to be killed sooner or later.

The dissipated of the resistor power is in the range of 14W --> thus the 2W resistor will be killed, too.

This is very basic electronics stuff. You really should know this .. especially when dealing with dangerous high voltage.
I expect there is even more lack of technical knowledge... thus you risk your and otherīs lives.

Please learn how to calculate and deal with voltage, current, resistance, power, AC waveform.. and how to treat dangerous high voltage (circuits)...

Klaus

Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.

Re: Optocoupler with LIVE wire

Originally Posted by KlausST

Hi,

sadly still no useful specifications.

Your calculation of the resistor is wrong.
You calculated 5.5kOhms.

this gives 280V/5500Ohms = 50.1mA

According datasheet 50mA is the absolute maximum limit. Once you cross this limit, just for a short moment - you risk to kill the device.
50mA is NOT the usual operating current.
Now you should know that 280V is the RMS voltage and thus the maximum voltage is 280V x 1.414 = 396V
at 5.5kOhms this gives a maximum current of about 72mA --> expect the PC814 to be killed sooner or later.

The dissipated of the resistor power is in the range of 14W --> thus the 2W resistor will be killed, too.

This is very basic electronics stuff. You really should know this .. especially when dealing with dangerous high voltage.
I expect there is even more lack of technical knowledge... thus you risk your and otherīs lives.

Please learn how to calculate and deal with voltage, current, resistance, power, AC waveform.. and how to treat dangerous high voltage (circuits)...

Klaus

What specification I have to give..?
About design or something else..?

Re: Optocoupler with LIVE wire

This is my circuit.When the Input signal is available means the LED have to glow...
Normally input supply will be 230VAC.But the voltage may vary from the 160VAC to 280VAC(Maximum Voltage).
The controller have to sense the available of input voltage,and have to glow the LED,if the voltage is varying also means.

Re: Optocoupler with LIVE wire

2x 5.5k series resistor seems to keep the maximum input current ratings, but due to wide PC814 CTR range of 20 to 300%, there's no way to get a useful input voltage threshold (if required). You have apparently calculated the resistors to work with minimal CTR of 20%, the backside is that an opto coupler with 300 % CTR reduces the input threshold to below 15 VAC.